Hyaluronate has been found to influence various aspects of cell behavior, including adhesion, phagocytosis and migration. These effects are probably mediated by a cellsurface receptor for hyaluronate which has been identified as an 85,000 Mr glycoprotein. Recent experiments have shown that the hyaluronate receptor is associated with actin filaments. Thus, the receptor may be responsible for a transmembrane interaction between extracellular hyaluronate and the intracellular actin filaments, which may in turn be important in regulating cell behavior. The goals of the present application are to further examine the hyaluronate receptor with respect to 1) its association with other proteins, 2) its distribution on the cell surface under different conditions, and 3) its role in regulating cell adhesion and migration. The first series of studies will examine the interaction of the receptor with other proteins. Preliminary experiments have shown that when cells are extracted with detergents under mild conditions, the receptor is present in a large complex. This complex will be isolated by molecularsieve chromatography and ratezonal centrifugation and the proteins which are present will be analyzed by SDSPAGE. In addition, proteins which interact with the receptor will be identified by binding experiments using an istopically labeled preparation of the receptor. The results of this study should reveal how the receptor interacts with Factin and other proteins. The next series of studies will examine the distribution of receptors on the surfaces of cells subjected to different conditions. First, to determine if Factin and/or hyaluronate controls the distribution of receptors, cells will be treated with drugs which alter these macromolecules, and the effect on the receptor distribution will be investigated. Secondly, the effects of viraltransformation on the distribution of receptors will be examined. And thirdly, migrating cells will be tested to determine if the receptors are distributed in a characteristic pattern. In each case, the receptors, will be visualized by immunofluorescent staining with a monoclonal antibody (K-3), specific for the receptor. The final series of experiments will examine the role of the receptor in mediating cell behavior. For this we will investigate the effects of the K3 monoclonal antibody and other substances which specifically interact with the receptor on 1) the heterotypic adhesion between tumor cells and endothelial cells, and 2) the rate of cell migration. The results of this study should answer a number of questions concerning the mechanism by which hyaluronate regulates cell behavior. This in turn may be of importance to several aspects of oncogensis, including tumor cell invasiveness, metastasis and angiogensis.